1. Field of the Invention
The present invention relates to the field of telecommunications, and more particularly to muting transmissions from a cellular telephone.
2. Description of the Related Art
Conference bridging platforms allow multiple parties to be simultaneously connected to a telephone call in which the parties can hear and talk to each other even though they are geographically displaced at a variety of locations. The telephone call to which the parties are simultaneously connected is known as a conference call. Conference bridging platforms are typically operated by telecommunications carriers as part of a conferencing service. A party can participate in a conference call by calling the conferencing service and identifying the particular conference call to which the party wants to be connected. Before a party can participate in a conference call, arrangements ordinarily need to be made with the confddderencing service to set aside resources on the conference bridging platform to support the conference call as well as billing functions.
Problems can arise in using a typical conference bridging platform when one of the parties to a conference call is a cellular phone user. For example, problems arising in two different situations can have a detrimental effect on the other parties participating in the conference call. First, the cellular phone user is often in an environment with high ambient noise levels, such as taxicabs, airports, or restaurants. Consequently, the signal received at the bridging platform is likely to be very noisy. Second, the user may be operating from an area at the edge of a cell or other areas within the interior of a cell where the user""s signal received at the base station is relatively noisy. In such situations, even if a party is not talking the signal received at the bridging platform may be very noisy because of the air link noise due to the poor link margin. These problems emanating from the operation of the cellular phone party can have a detrimental effect on the remaining parties participating in the conference call.
This detrimental effect arises because of the manner in which typical conference bridging platforms retransmit the signal received from one party to the remaining parties on the conference call. During the conference call, typically, a party can be heard by the other parties if the party""s speech or sound level is the highest or the second (or maybe even the third) highest in comparison to the sound level of the other parties to the conference call. The party can be heard by the other parties because the conference bridging platform selects and rdddetransmits the signal which has the highest or second highest sound level to the remaining parties while the signals of the remaining parties are muted. This approach has the drawback of cellular phone conferees having loud or noisy connections, which often happens as described above, frequently dominating other conferees to the point where the latter are not heard by the noisy conferees.
This problem is pervasive and happens often whenever a cellular phone user is party to a conference call supported by a typical conference bridging platform. Foladare et al., U.S. Pat. No. 5,724,416, describes a conference bridging platform specifically designed to provide a solution to the dominating effect caused by conferees having loud or noisy connections. The invention of Foladare et al. resides in the conference bridging platform illustrated in FIG. 1 of U.S. Pat. No. 5,724,416. The platform includes a conventional conference bridging system, a plurality of noise adapters and a controller.
Subscribers access the conference bridge platform in a well-known manner by dialing a designated number. If the user of the cellular phone is in a high noise environment or an area of a cell with a poor link margin, such a user can avoid dominating the conference call by entering a predetermined touchtone or DTMF key, for example, the xe2x80x9c#xe2x80x9d key. The platform responds to entry of a touchtone xe2x80x9c#xe2x80x9d or other similar signal by muting the conference call branch in which the xe2x80x9c#xe2x80x9d was entered.
Alternatively, the platform responds to entry of a touchtone xe2x80x9c#xe2x80x9d or other similar signal by balancing the sound levels of the telephone calls participating in the conference call. Balancing is performed by the noise adapters and controller adjusting the threshold which a conferee""s sound level must overcome in order for the conferee to participate the conference call. Balancing results in the threshold of less noisy conferees being lowered relative to the threshold of noisier conferees so that the less noisy conferees can participate in the conference call without having to raise their voices significantly.
Unfortunately, there are many conference bridging platforms in use which do not incorporate manual muting, e.g., the invention described in Foladare et al. These platforms perform adequately until a conference call includes a cellular phone party whose signal is noisy. In such a situation, for all conferees to be heard, conferees who are dominated by the louder connection of a cellular phone party must typically raise the volume of their voices significantly. Otherwise, the conferees will hear only the noise emanating from the cellular phone party""s dominating connection. Consequently, there is still a need for improved conference bridging platform support of conference calls which include a cellular phone party whose signal is noisy. This invention meets this need.
In the current state of the art there are two methods that are currently contemplated for muting the transmissions of a cellular telephone. First, the microphone input can be disengaged from the speech encoder input. In the case of advanced vocoders, this prohibits the vocoder from being able to track changes in the background noise. In addition, the transmitter still transmits packets indicative of the silence. These packets may be erroneously decoded that can result in very disturbing noise effects. In variable rate vocoders, a rate determination error can cause a very disturbing effect.
A second method of muting a cellular phone would be to cause its transmission to temporarily cease. However, in an analog phone this would result in the disastrous consequence of the base station tracking pure noise and providing it to the end user. In digital systems this would cause the call to drop based on a lost reverse link. Both of these solutions are unsatisfactory. Thus, there is a need for a method of muting the transmissions of a cellular telephone in an effective manner.
The system and method of the present invention provide a simple, but effective, technique for allowing a user of a wireless communication device to mute the transmission from his cellular telephone. One particularly advantageous application of the present invention is to prevent the user""s domination of a conference call being supported by a conference bridge accessed using a wireless communication system. The user""s domination of the conference call results in the other conferee""s of the conference call not being heard by the user and/or other conferees. This invention does not require modification of the conference bridge.
In addition, the present invention applies to calls to a speaker phone where a cellular user calling into a meeting room can use the present invention to prevent noise associated with the user""s noisy environment, or noise inserted in the over-the-air interface from generating loud, disruptive audio at the meeting room.
An additional benefit of the present invention is that the protocol enhancement allows the user to achieve privacy, even on regular phone conversations. The electronic microphones at cellular phones are so sensitive, that covering the microphone with a hand does not ensure that the audio is muted. Since this is implemented at the infrastructure, the feature is available to all users of cell phones, since it is proposed using regular DTMF digits to turn the audio on/off.
In case of the cellular user operating on an analog cellular system, such as AMPS, there is high chance of a constant noise being added to the user""s audio. This is improved in digital systems, such as CDMA systems, they are more resistant to the over-the-air noise, but they are not completely immune to such noise, and if the noise becomes significant, it can generate audio signal with very high energy. The invention addresses both of these sources of noise.
In one embodiment, the wireless communication system is capable of receiving a signal from the wireless communication device at the instruction of the user. In response to the received signal, the wireless communication system mutes the user""s signal preventing the noise associated with the wireless communication device from reaching the conference bridge. The noise associated with the wireless communication device can include ambient noise at the device or air link noise between the device and the wireless communication system. This noise often results in the user of a wireless communication device dominating a conference call in which the user is participating.
Thus, a user of a wireless communication device can prevent the user""s domination of a conference call by muting the user""s signal at the wireless system. By muting the user""s signal at the wireless system, this invention allows the wireless communication device user to prevent the user""s domination of conference calls even if the user is using a conference bridge that does not, itself, prevent domination of conference calls.